This invention relates to the field of feeding mechanisms for shaft furnaces. More particularly, this invention relates to a new and improved feeding device for shaft furnaces in which a vertical feed channel leading to a rotary or oscillating distributing spout is mounted on the head of the furnace on the vertical axis of the furnace.
In the prior art, the rate of material to be fed to the furnace, flowing from the storage enclosure to the spout, has been regulated by a dosing device, usually of the type described in French Pat. No. 73 07 717. This dosing device has been mounted in a slanting passage connecting the base of the storage enclosure to the vertical feed channel above the spout. This slanting passage has been the cause of many problems associated with the distribution of furnace charge material. These problems are discussed in detail in UK Patent application No. A-2085135.
Various attempts have been made to solve these problems such as, for example, providing guide blades as shown in the aforementioned UK Patent application No. A-2085135 or by providing a type of tubular plug as disclosed in French Pat. No. 76 20 742. All of these prior attempts are aimed at correcting the flow path and direction of the falling material to be fed to the furnace in order to ensure that it falls vertically and symmetrically onto the spout. Unfortunately, these attempts have not proved satisfactory nor are they capable of providing the improved results which could be expected if the storage enclosure and its flow orifice were situated on the vertical axis, thereby enabling the material fed to the furnace to fall vertically and centrally onto the spout.
In the past, a vertical axis feed mechanism was thought unattainable for two reasons. First, the majority of feeding or charging mechanisms in which a spout is employed comprise two juxtaposed storage enclosures operating alternatively, and it is not possible to position two such adjacent enclosures on the axis of the furnace. Second, the dosing devices in the prior art can only operate by the pentration of a flow moving in an oblique direction. Consequently, even if there is only one single storage enclosure, as shown in French Pat. No. 79 29 853, the storage enclosure has to be made eccentric in order to provide the inclined section required for the operating of the dosing device.